The
developer of the well known SDR Airspy-R2 has announced a new receiver,
developed in cooperation with ITead Studio and a leading semiconductor
manufacturer - the Airspy HF+.

The Airspy HF+ operates from 9 kHz to 31 MHz and from 60
to 260 MHz. The new design of the SDR receiver is based on a "Zero-IF" concept,
whereby the received signal is mixed directly into the baseband range. This
technology avoids many of the problems of classic receiver designs, but also
presents developers with new challenges. The Airspy HF+ meets these challenges
by using three analog tuners with fixed and tunable band filters. The mixers are
designed as harmonic rejection mixers and thus ensure an extraordinarily good
linearity and spectral purity of the down-mixed signal. This is important for a
good sensitivity, because the cleaner the signal, the less likely it is that a
weak signal will be lost in the noise. Two very capable AD-converters are used
for digitizing the baseband signal. The subsequent decimation stages (DDC) work
with different methods for reducing (decimating) the data rate. The result is a
very effective anti-aliasing filter that provides approximately 108 dBc
reduction. The resulting signal has a resolution of 18 bits, which is then
scaled to 16 bits for transmission via the USB 2 interface.

Such a receiver design requires a very precise AGC to
achieve the best possible sensitivity and high dynamic range. The software of
the Airspy HF+ microcontroller controls the amplification in each stage of the
tuner and the subsequent filters and amplifiers. The result is a dynamic range
of theoretically 113 dB, practically 110 dB is achieved (on shortwave). This is
an excellent result for such a compact receiver of this price range. The user
benefits from the very good linearity and the high dynamic range as the received
spectrum is much cleaner and free of artifacts. Manual gain control is not
necessary, nor is the use of attenuators, preamplifiers, selective band filters
etc.

In addition to the excellent RF characteristics, the
developers have achieved an equally remarkable noise reduction at the AF level.
Here, the disturbing noise in a desired signal is largely eliminated, without
the signal suffering from intelligibility and without too many artifacts in the
AF. The best way to hear the effect is to listen to the sample povided below.

Another highlight of the Airspy HF+ is the free
software "SpyServer", which offers an easy to set up remote server. Here, a
small computer (a cheap Raspberry PI or similar) can take over the function of
the server to which the Airspy HF+ is connected. The receiver can then be
accessed via the network in the usual way, even with several listeners at the
same time. The difference to other web-based concepts is that the transferred
data is actually an IQ signal, which can then be processed by the usual SDR
software with all plug-ins. You are not hindered by the limitations of a web
browser as SDR software.

Technical Data Airspy HF+

HF

0.009 – 31 MHz

VHF

60 – 260 MHz

MDS

@500 Hz, 0–31 MHz

-140 dBm

MDS

@500 Hz, 60–108 MHz

-141.5 dBm

MDS

@500 Hz, 118–136 MHz

-142.5 dBm

MDS

@500 Hz, 136–174 MHz

-140.5 dBm

MDS

@500 Hz, > 175 MHz

-140 dBm

IIP3

0–31 MHz

+15 dBm

IIP3

60–260 MHz

+13 dBm

BDR

0–31 MHz

110 dB

BDR

60–260 MHz

95 dB

Width of waterfall/spactrum

48, 96, 192, 384 & 768 kHz (max. 660 kHz
alias-free)

Oscillator Accuracy

0.5 ppm

Antenna connectors

2x SMA (HF, VHF)

Impedance

50 Ω

Temperature range

-45 – +85°C

Airspy HF+ SDR

259.00

Software

The Airpy HF+ can be used with many different programs on
different operating systems. SDR# is probably one of the most suitable,
since it comes from the same developer.

The
SRH-789 is a wide band telescopic antenna for scanners and similar devices. The
adjustable frequency range is from 90 to 1100 MHz, the resonant frequency is set
by changing the length of the telescope. Retracted length 20cm, fully extended
length 80.5cm. A helpful table for various lengths and frequencies is printed on
the loermost element of the antenna. The connector is SMA male, with locking
nut, which allows the antenna to be adjusted in any position on the SMA socket.
A knuckle helps adjusting the antenna vertically or in any other direction.

The
Bonito ML-FX is a wide band active antenna for reception of long, medium and
short waves as well as the lower VHF band. The antenna is is characterized
by a small apcking size, low noise and excellent signal levels.

The ML-FX consists of a flexible, braided steel wire
loop with large wire gauge, length 5m. The loop is connected to the
amplifier, both are installed by hanging the wire to the wall, into a
window, in a tree or on another suitable supports. The amplifier is supplied
over the coaxial cable (not included) from a supplied Bias-T. This Bias-T
has connectors for an external supply voltage as well as a socket for a USB
cable. The voltage can range from 5 to 15 V. The USB connector makes the
antenna very well suitable for portable operations with a computer.

Despite the high amplification (adjustable in three
steps), the ML-FX has a very low noise level, as comparisions to other
active antennas have shown. The antenna can be used from long wave (9 Khz)
up to the lower VHF range of 180 MHz. The amplifier has a very high 3. order
intercept point of +40dBm. This results in a very high distortion free
blocking dynamic range. The amplifier is protected by a twofold overvoltage
protection. With this protection the antenna not only survives a
thunderstorm but can also be used in vicinity to transmitting antennas, for
example in the garden of a radio amateur or on a sailing yacht. Additionally
a VHF broadcast band stop filter can be activated.

With the small packing size and the USB power supply
the ML-FX is very well suited to accompany you in a vacation. For example
the antenna can be easily installed with two suction cup holders in a
window. The coaxial cables are not supplied because most customers require
different lengths. Whe does provide several ready made cables, and can also
manufacture a cable tailored to your requirements.